1. Technical Field of the Invention
The present invention relates in general to the mobile telecommunications field and, in particular, to a method for utilizing a plurality of overlapping mobile networks.
2. Description of Related Art
Competition has been a driving force behind the fast developing field of telecommunications. Deregulation has opened up the telecommunications market and now allows independent operators to establish competing networks. The wireless telephony market is one that is fiercely competitive. As a consequence of deregulation, it is becoming more common for numerous co-existing, independent wireless networks to overlap in coverage. This deregulated environment provides opportunities for mobile phone users to select the most appropriate network operator (e.g., in order to obtain the lowest cost at any particular time). A prerequisite for such flexibility is an agreement to cooperate between at least two independent network operators, so that a user having a subscription a with a first network operator can, while visiting in a network owned by a second operator, connect to that second network. In principle, a mobile user could then select the most appropriate network at each instant to make outgoing mobile calls. However, one problem is that the same flexibility does not apply to an incoming call, because such a call must include an identity appropriate to the network indicated on the receiving mobile phone's Subscriber Identity Module (SIM) card.
A user's mobile phone includes a unique SIM card, which is a key for gaining access to a network to which the user subscribes. While visiting in other networks, if cooperative agreements exist, the user can make and receive wireless calls. However, one existing problem is that some mobile network operators (e.g., in Sweden) do not allow a user to select between networks in regions where there are several competing networks available. An exception is made only for visitors that subscribe with foreign (e.g., non-Swedish) network operators having cooperation agreements with the Swedish network operators.
Another existing problem is that double mobile phone fees can be invoked for an incoming call to a mobile user. This problem arises when a mobile call is made to a user who is visiting in a network other than the one where the user's subscription is registered. This problem is illustrated by FIG. 1, where in order to call mobile user B, the user of fixed telephone A uses the identity of user B's mobile phone. In this case, the identity of user B's mobile phone is supposed to direct the call to network N0. This first call is charged as a mobile phone call. Network N0 has updated location information about user B's mobile phone, which is used by network N0 to forward the call to network Ni where user B's mobile phone is currently logged in. User B will be charged for a mobile call between network N0 and network N1. Consequently, the completed call invokes charges for two mobile connections. In addition to this shortcoming, the user of fixed telephone A has no opportunity to select the most appropriate network (e.g., N1, N2, N3) even if they are all available due to an assumed agreement of cooperation between the respective network operators.